My home-build HF PA.




The frontview of the almost finished amplifier. ( PA tuning&input tuning scale not yet finished)


The HV section, the separate fuses for the transformers are visible at right lower corner

1 Another view of the finished amplifier.2


The anode current is adjustable at the frontpanel, the meter-scale and other front-panel text is home made with special software made by F5BU called GALVA. It is freeware and downloadable on his website.

I used water-slide decal paper for transferring the printed text on the front and meter scales.

softstart is a must with this size of transformers !

 SWR bridge measuring forward & reflected power.  It is equipped with an extra output selection relay and a T/R relay.

 SWR bridge placed in the amplifier

The some testing and....

.... RF calibrating the SWR bridge and RF power metering

Finally a pic of milling one of the 6 toothwheels, this one is for the input tuning dail lower right on the frontpanel.



           Schematic of adjustable bias control; ALC;  SWR protection and T/R control




 Schematic of power supply.